Altered Cell-Cycle Control, Inflammation and Adhesion in High-Risk Persistent Bronchial Dysplasia

Persistent bronchial dysplasia (BD) is associated with increased risk of developing invasive squamous cell carcinoma (SCC) of the lung. We hypothesized that differences in gene expression profiles between persistent and regressive BD would identify cellular processes that underlie progression to SCC. RNA expression arrays (Affymetrix Hu 1.0) comparing baseline biopsies from 32 bronchial sites that persisted/progressed to 31 regressive sites showed 395 differentially expressed genes (ANOVA, FDR=0.05). Thirty-one pathways showed statistically significant evidence of altered activity between the two groups. Multiple pathways were associated with cell cycle control/proliferation, inflammation, or epithelial differentiation/cell-cell adhesion. Polo-like kinase 1 (PLK1) was associated with multiple cell cycle pathways. Cultured persistent BD cells showed increased PLK1 expression, and following treatment with PLK1 inhibitor, showed induction of apoptosis, G2/M phase arrest and decreased proliferation compared to untreated cells. These effects were not seen in normal or regressive BD cultures. Inflammatory pathway activity was decreased in persistent BD and the presence of an inflammatory infiltrate was more common in regressive BD. Regressive BDs were also associated with trends toward overall increases in macrophages and T-lymphocytes and altered polarization of these inflammatory cell subsets. Increased desmoglein 3 and plakoglobin expression was associated with higher grade and persistence of BD. The results identify alterations in cell cycle control, inflammatory activity, and epithelial differentiation/cell-cell adhesion in the persistent subset of BDs that are associated with high risk for progression to invasive SCC. These pathways may provide strong markers of risk and effective targets for lung cancer prevention. Lung biopsy gene expression profiles. We performed two primary analyses. The first compared persistent/progresive sites defined as those with follow-up (F/U) scores of 4 (mild bronchial dysplasia) or greater to regressive sites with F/U scores of 1 or 2 (normal or reserve cell hyperplasia). The second analysis looked for genes whose expression was correlated with change in baseline (BL) diagnosis. This was based on the BL Frozen Dx. The diagnosis scores are: 1=normal, 2=reserve cellhyperplasia, 3=squamous metaplasia without atypia, 4=mild dysplasia, 5=moderate dysplassia, 6=severe dysplasia and 7=carcinoma-in-situ. X.1 indicates the biopsy showed features of angiogenic squamous dysplasia. Group 1 = Persistent bronchial dysplasia (BL >/= histology score 4, FU >/= histology score 4) Group 2 = Regressive bronchial dysplasia (BL >/= histology score 4, FU = histology score 2) Group 3 = Progressive non-dysplasia (BL = histology score 2, FU >/= histology score 4) Group 4 = Stable non-dysplasia (BL = histology score 2, FU = histology score 2)